SNAKES OF CEYLON. 269 



set. Palatine : Anododont, strongly scaphiodont. Ptery- 

 goid : Anododont, scaphiodont. Mandibular : Anododont, 

 strongly scaphiodont. 



Distribution. — Tropical Africa, South Asia, Papuasia, 

 Australia. 



There are about twenty-eight species, of which seventeen 

 occur within Indian limits, and five of these in Ceylon. 



Dipsadomorphus trigonatus (Schneider). 



(Latin. Adjectival form of " trigonum " a triangle, from the 

 somewhat triangular dorsal marks.) 



The Gamma Snake or Common Indian CatsnaJce* 



Synonymy. — Coluber trigonatus, C, Sagittarius, C. caten- 

 ularis, Dipsas trigonata. 



History. — First brought to scientific notice by Russell, who 

 figured it in 1796 in his first volume on Plate XV. Christened 

 by Schneider in 1802. 



General Characters. — A small snake growing to about 3 feet 

 in length. Head depressed ; subcordate in shape, widest 

 midway between the eye and the neck. Snout shortish, 

 without canthus, obtusely rounded. Neck markedly con- 

 stricted. Nostril lateral, almost wholly contained in the 

 anterior nasal shield ; occupying the second- and third-fifths 

 of the suture from above downwards. Eye large, with 

 mustard -yellow iris and vertical pupil. Body slender, 

 elongate, and markedly compressed ; attenuating towards 

 the neck and the vent. Belly rounded. Tail moderate in 

 length, being about one -seventh to less than one -sixth 

 the total length. 



* The marks on the body are very like a Greek *{, especially those on 

 the right side. I call the species of this genus the catsnakes because 

 they are cat-like in the following traits : They are arboreal in habit, 

 exhibit a fierce nature, are mainly nocturnal, and possess a large eye, 

 with a vertical pupil and mustard-coloured or greenish iris. 



